Only the grille and headlights pretend to keep faith with what came before. Viewed head on, there's no mistaking STS for anything but a Cadillac. The trademark egg-crate grille and stacked headlamps are starkly functional in appearance. No wasted motion or volunteer excess there, to be sure.

You could be forgiven, however, for mistaking an STS for the smaller CTS. The two are almost indistinguishable to the casual observer, even when parked side by side. Both cars present only minimally different iterations of the same sharp angles and flat planes. The wheelbase of the STS is three inches longer, and its body is six inches longer, but they share a common platform.

From the side, the crisp lines of the STS draw an almost box-like silhouette that somehow still looks aerodynamic. Perhaps it's the gently curved A-pillar and C-pillar that tend a bit more toward art than science. Sharply contoured lower rocker panels tracking rearward from the front fascia's bottom edge pull the body down, adding a stylistic ground-effects look.

The backside is vaguely reminiscent of the old Eldorado coupe, with vertical taillights bracketing a tall, squared-off boot. Recessed in the boot's rear vertical is a trapezoidal inset, long enough for European-spec license plates, housing large backup lights at the left and right extremes. American-tradition dual exhausts exit below and at each end of the rear bumper. The optional rear spoiler, running the width of the trunk lid, adds stabilizing rear downforce without spoiling the look.

The super-performance STS-V is distinguished from the other STS models by its unique engine hood; a larger, polished stainless steel wire-mesh front grille; a lower front fascia with a larger, lower grille, brake ducts and splitter; lower side rockers; 10-spoke wheels; a higher rear spoiler; a lower rear fascia with wire-mesh accenting; and V-Series badging along with Supercharged badges on the doors.